fix(build): drop invalid --no-incremental from dotnet publish (MSB1001)

dotnet publish rejects --no-incremental (it's a dotnet build switch) -> MSB1001 Unknown
switch -> build failed. The bin/obj wipe alone forces the clean recompile we need.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

windows/installer/build.ps1

@@ -162,10 +162,11 @@ function Invoke-PublishWelcome {
     $out  = Join-Path $WorkDir 'welcome-publish'
     # Force a CLEAN compile. The CI runner reuses build artifacts across runs, and dotnet's
     # incremental build has shipped a STALE SilverOS.Welcome.Core.dll (old code despite fixed
-    # source) -- so wipe every bin/obj under welcome/ and pass --no-incremental.
+    # source) -- so wipe every bin/obj under welcome/ before publishing (a clean tree forces a
+    # full recompile; note `dotnet publish` does NOT accept --no-incremental).
     Get-ChildItem (Join-Path $WindowsDir 'welcome') -Recurse -Directory -EA SilentlyContinue |
         Where-Object { $_.Name -in 'bin', 'obj' } | Remove-Item -Recurse -Force -EA SilentlyContinue
-    & dotnet publish $proj -c Release -f net9.0-windows10.0.19041.0 -r win-x64 --self-contained true --no-incremental -o $out
+    & dotnet publish $proj -c Release -f net9.0-windows10.0.19041.0 -r win-x64 --self-contained true -o $out
     if ($LASTEXITCODE -ne 0) { throw 'Welcome app dotnet publish failed' }
     Write-Host "   Published to: $out"
 }